Lock stitch sewing machines



Aug. 4, 1964 F. PARRY LOCK STITCH SEWING MACHINES 2 Sheets-Sheet 1 Filed March 5, 1962 INVENTOR. FRANK PARRY ATTORNEY WITNESS Aug. 4, 1964 F. PARRY LOCK STITCH SEWING MACHINES 2 Sheets-Sheet 2 Filed March 5, 1962 I 5 I INVENTOR.

FRANK PARRY ATTORNEY United States Patent 3,143,093 LOCK STITCH SEWING MACHINES Frank Parry, Morris Plains, N.J., assignor to The Singer Company, a corporation of New Jersey Filed Mar. 5, 1962, Ser. No. 177,569 2 Claims. (Cl. 112181) This invention relates to lock stitch sewing machines of the type including mechanisms for automatically replenishing the supply of locking thread on a bobbin in place in the loop taker, and more particularly to a novel and improved mechanism for effecting an interruption in the reciprocation of the needle bar during the replenishment of thread on the bobbin.

It is an object of this invention to provide a bobbin thread replenishing mechanism operative during continued motion of the sewing machine loop taker as is required for the formation of lock stitches and in which the drive for the needle bar is interrupted during the bobbin thread replenishing operation.

It is a further object of this invention to provide a device of the above character in which the sewing machine needle bar will be stopped during replenishment of the bobbin thread in a predetermined position regardless of when during the cycle of needle reciprocation the bobbin thread replenishing mechanism is initiated.

A still further object of this invention is to provide a novel and improved interrupting device for the drive of an endwise reciprocatory needle bar of a sewing machine.

In the accompanying drawings of a preferred embodiment of this invention,

FIG. 1 represents a side elevational view of a sewing machine with a portion of the bracket arm illustrated in vertical cross section and having this invention applied thereto,

FIG. 2 represents an enlarged end elevational View of the bracket arm portion of the sewing machine of FIG. 1 with the hinged end cover removed and the top cover broken away,

FIG. 3 is an enlarged cross sectional view taken substantially along lines 33 of FIG. 2, and

FIG. 4 is an enlarged cross sectional view taken substantially along lines 44 of FIG. 2, and

FIG. 5 is a cross sectional view taken substantially along the line 5--5 of FIG. 4.

Referring to the drawings FIG. 1 illustrates a sewing machine having a casing including a bed 11 from which rises a vertical standard 12 having a bracket arm 13 extending therefrom over the bed. A shaft 14 rotatable in the bracket arm is adapted to be driven by a motor 15 and is operatively connected by means of bevel gears 16, a vertical shaft 17 in the standard, and bevel gears 18 to a bed shaft 19 which is, in turn, connected by bevel gears 20 to a loop taker shaft 21 which carries a loop taker 22. The loop taker may be of the type disclosed and described in the co-pending United States patent application of S. J. Ketterer, Serial No. 133,896 filed August 25, 1961, to which reference may be bad. This loop taker 22 includes a bobbin 23 journaled therein and cooperates with a mechanism in the sewing machine which as fully described in the above referenced co-pending United States patent application, serves to replenish the supply of locking thread in place on the loop taker at the will of the sewing machine operator.

For a comprehension of this invention it will be sufiicient to understand that a control dial 24 is journaled in the sewing machine standard by which the operator of the sewing machine may at will turn a cam 25 to depress or release a lever 26. Depression of the lever 26 shifts downwardly in the machine standard a link 27. At the lower extremity the link 27 is pivoted to a bobbin thread replenishing lever 28 pivoted in the bed at 29 and connected to a rod 30 of a bobbin winding member 31 which is journaled axially in the loop taker shaft 21. At the upper extremity the link 27 is pivoted to a lever 32 fulcrumed at 33 in the bracket arm and connected to a slide bar 34 constrained by means of slots 35 and fastening screws 36 in the bracket arm and having a lip 37 underlying one arm 38 of a needle thread tension release lever 38, 39. The lever 32 and slide bar 34 thus serve upon initiation of bobbin thread replenishing operation to release a needle thread tension device 40 by means of a tension release pin 41 engaged by the bell crank 38, 39. The thread tension device 40 provides for control of a sewing thread which is carried by a needle 42 secured to an endwise reciprocatory needle bar 43 in the bracket arm. The needle bar isdriven by means of a connecting link 44 pivoted on the needle bar and on a crank pin 45 fast in crank member 46 on the shaft 14. The crank pin 45 is also embraced by a needle thread take-up lever 47 which influences the thread between the tensioning device and the needle.

The shaft 14 is lengthwise slotted as at 50 to accommodate a detent 51 formed on a latch lever 52 pivoted at 53 on the crank member 46. The free extremity 54 of the latch lever 52 is biased by means of a coil spring 55 to engage the detent into the slot 50 thus connecting the needle bar and the take-up lever to the shaft 14 for operation in timed relation with the loop taker as is required for the formation of lock stitches.- t

Upon initiation of the bobbin thread replenishing process by operator influenced turning of the control dial 24, a pin carried by the slide bar 34 serves to elevate one arm 61 of a composite bell crank lever 61, 62 fulcrumed on a pin 63 carried by the bracket arm 13, the bell crank arm 61 being bifurcated and embracing the pin 60. The bell crank arm 62 is thus shifted into the path of the free extremity 54 of the latch lever 52 when the slide bar 34 is lifted upon initiation of the bobbin thread replenishing mechanism.

Should the bobbin thread replenishing mechanism be initiated by the operator when the arm 62 of the bell crank 61, 62 is disposed opposite the counterweight portion of the crank member 46, a leaf spring 64 connecting the lever 32 with the slide bar 34 will accommodate any such interference. Upon continued rotation of the crank member 46, however, the bell crank arm 62 will move into a position with the bell crank arm 62 in the path of motion of the free extremity 54 of the latch lever 52 for engagement therewith as the needle 42 ascends above the bed 11 and out of any work fabrics thereon being stitched. The bell crank arm 62 will thus depress the latch lever 52 to effect interruption of the drive of both the needle bar and takeup lever, and will maintain such drive interruption as long as the bobbin thread reciprocating process continues. When the slide bar 34 is lowered upon termination of the bobbin thread replenishing operation, the latch lever 52 will be released and a return spring 65 on the bell crank 61, 62 will assist therein so that the detent 51 will enter the slot 50 and reestablish driving relation of the needle bar, take-up lever, and loop taker when these parts assume proper timed relation for the formation of lock stitches.

It is pointed out that as described in the above referred to co-pending United States patent application Serial No. 133,896, the bobbin is replenished with thread from the needle. In order properly to initiate bobbin thread replenishment, therefore, at least one reciprocation of the needle is necessary. With the present invention such a needle penetration prior to interruption of the needle bar drive is assured as a practical matter by virtue of fact that interruption of the needle bar drive is timed to occur immediately as the needle ascends from the bed. Although, the operator is free to operate the control dial 24 at any time in the cycle of stitch formation, as a matter of fact,

it is only practical for her to initiate a bobbin winding cycle with the needle out of the bed or out of any goods which may be on the bed. Thus, in all cases of actual use the needle will partake of a large portion of a complete reciprocation before the interruption means becomes effective and the needle thread will be thus carried to the loop taker to provide for the supply of thread to be wound on the bobbin.

Having thus set forth the nature of my invention, what I claim herein is:

1. In a lock stitch sewing machine having a frame, an endwise reciprocatory needle bar, a loop taker having a bobbin journaled therein and means including a shaft rotatable in vsaid frame for operatively connecting said needle bar and said loop taker for movement in timed relation as is required for the formation of lock stitches, means for actuating said needle bar and loop taker connecting means, mechanism for replenishing thread on said bobbin in place in said loop taker during actuation of said needle bar and loop taker connecting means, control mechanism carried by said sewing machine for rendering said thread replenishing mechanism effective and ineffective, a releasable driving connection between said rotatable shaft and said needle bar driving crank means including a latch lever pivotally supported on said crank means and formed with a detent biased into and out of interlocking relation with a recess formed in said shaft, a release member shiftably supported on said sewing machine frame, and means operatively connected with the control mechanism for said bobbin thread replenishing mechanism for shifting said release member into the path of said latch lever to effect movement of said latch lever detent out of interlocking relation with said shaft recess when said bobbin thread replenishing mechanism is rendered elfective.

2. In -a lock stitch sewing machine having an endwise reciprocatory needle bar, a loop taker with a bobbin journaled therein, and drive mechanism for operatively connecting said needle bar and said loop taker for movement in timed relation as is required for the formation of lock stitches, mechanism operable for replenishing thread on said bobbin in place in said loop taker during said movement of the loop taker in response to operation of said drive mechanism, means for initiating and for terminating operation of said bobbin thread replenishing mechanism, drive separation means operative in only one predetermined position of reciprocation of said needle bar for separating said needle bar from said drive mechanism, and means for rendering said drive separation means effective upon that movement of said needle bar into said predetermined position of reciprocation which next succeeds each initiation of the operation of said bobbin thread replenishing mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 1,794,255 Stephenson Feb. 24, 1931 2,318,200 Cobble et al May 4, 1943 3,016,029 Card Jan. 9, 1962 3,038,429 'Kettereret al. June 12, 1962 

1. IN A LOCK STITCH SEWING MACHINE HAVING A FRAME, AN ENDWISE RECIPROCATORY NEEDLE BAR, A LOOP TAKER HAVING A BOBBIN JOURNALED THEREIN AND MEANS INCLUDING A SHAFT ROTATABLE IN SAID FRAME FOR OPERATIVELY CONNECTING SAID NEEDLE BAR AND SAID LOOP TAKER FOR MOVEMENT IN TIMED RELATION AS IS REQUIRED FOR THE FORMATION OF LOCK STITCHES, MEANS FOR ACTUATING SAID NEEDLE BAR AND LOOP TAKER CONNECTING MEANS, MECHANISM FOR REPLENISHING THREAD ON SAID BOBBIN IN PLACE IN SAID LOOP TAKER DURING ACTUATION OF SAID NEEDLE BAR AND LOOP TAKER CONNECTING MEANS, CONTROL MECHANISM CARRIED BY SAID SEWING MACHINE FOR RENDERING SAID THREAD REPLENISHING MECHANISM EFFECTIVE AND INEFFECTIVE, A RELEASABLE DRIVING CONNECTION BETWEEN SAID ROTATABLE SHAFT AND SAID NEEDLE BAR DRIVING CRANK MEANS INCLUDING A LATCH LEVER PIVOTALLY SUPPORTED ON SAID CRANK MEANS AND FORMED WITH A DETENT BIASED INTO AND OUT OF INTERLOCKING RELATION WITH A RECESS FORMED IN SAID SHAFT, A RELEASE MEMBER SHIFTABLY SUPPORTED ON SAID SEWING MACHINE FRAME, AND MEANS OPERATIVELY CONNECTED WITH THE CONTROL MECHANISM FOR SAID BOBBIN THREAD REPLENISHING MECHANISM FOR SHIFTING SAID RELEASE MEMBER INTO THE PATH OF SAID LATCH LEVER TO EFFECT MOVEMENT OF SAID LATCH LEVER DETENT OUT OF INTERLOCKING RELATION WITH SAID SHAFT RECESS WHEN SAID BOBBIN THREAD REPLENISHING MECHANISM IS RENDERED EFFECTIVE. 